The present invention is directed toward a system for generating correction pulses in an electronic timepiece, and particularly toward a system for generating correction pulses in an electronic timepiece having a digital display.
At the present time, electronic timepieces having digital displays have become extremely popular. In such timepieces, a crystal oscillator circuit provides a standard timebase signal, while a digital display of time or other information is provided by means of a liquid crystal display. In order to correct or modify a quantity which is computed by or stored in such a timepiece (such as current time or alarm time information) it is necessary usually to alter a number of digits. Various means of correction of such information have been proposed in the past. However the method which has most widely been adopted is that called the "select-and-set" system. In this system, two pushbuttons are employed, one being actuated to select the digit to be corrected, and the other being actuated to correct the selected digit. Such a system has various disadvantages. One of these is that the method is very different from the conventional method of correcting a timepiece, i.e. by rotating the timepiece crown, which is still the most familiar method for many people. Another is that it is generally necessary to actuate the setting pushbutton (i.e. the second one referred to above) a number of times in succession, in order to correct a particular digit. Yet another disadvantage is that such correction is generally unidirectional, i.e. correction is performed only by incrementing the digit being corrected, although various methods have been proposed for providing bidirectional correction, of varying degrees of complexity.
For the above reasons, a conventional method of correction, such as the set-and-select method described above tends to discourage prospective purchasers from buying an electronic digital timepiece, due to the apparent complicated operations necessary with such a method. It may be difficult for some prospective buyers to comprehend the correction method as explained in the instruction manual, particularly in the case of persons buying a timepiece for the first time. A correction or setting method which is relatively complicated and time consuming is especially undesirable in the case of setting alarm time information, in a timepiece having an alarm function, since the setting of such information must be performed relatively frequently.
It is therefore desirable to provide a system in an electronic timepiece having a digital display whereby correction of current time or other information can be carried out in a simple, uncomplicated manner, and that bidirectional correction should be possible without increasing the complexity of the correction procedure or increasing the number of operating members which must be actuated to perform correction. These requirements are met by the correction signal generating system of the present invention, which also provides the advantage that correction is performed by rotating a timepiece crown, a method which is familiar to very many people.